The present invention relates to a control apparatus for controlling an occupant protection device of a vehicle, such as an airbag and a seat-belt tensioner.
A conventional control apparatus for controlling an occupant protection device, as shown in The Japanese Patent Laid Open Publication No.8-85414, for example, has an acceleration sensor provided on a floor tunnel in a car room. The acceleration sensor detects an acceleration operating to a car body through the floor tunnel, and gives an analog signal representative of the acceleration to the control apparatus. The control apparatus integrates the acceleration signal from the acceleration sensor, detects occurrence of a collision requiring a drive of an occupant protection device based on a comparison between an integrated value of the acceleration signal and a predetermined collision decision threshold value, and drives the occupant protection device such as an airbag.
By the way, when an impact of collision is absorbed by a crush of a collision part of the car body, it can be assumed that a collision acceleration transmitted to the floor tunnel is weakened. In such a case, since an acceleration detected by the acceleration sensor provided on the floor tunnel is small, though there is no fear of it causing difficulties in occupant protection at time of collision, a fear of causing a delay in driving the occupant protection device exists. In particular, a collision, such as an offset collision or an oblique collision, tends to cause a case in which the acceleration transmitted to the floor tunnel is weakened. Because of this, from the viewpoint of improving control of the occupant protection device, regardless of whether the collision acceleration transmitted to the acceleration sensor provided in the car room is weakened, an exact control of the occupant protection device is desired.
It is an object of the present invention to provide an improved control apparatus of an occupant protection device.
Another object of the present invention is to provide a control apparatus that can exactly control the occupant protection device, regardless of whether a collision acceleration transmitted to an acceleration sensor provided in a car room is weakened.
The above and other objects are attained by a control apparatus of an occupant protection device having a room acceleration sensor, provided in a room of a vehicle, for detecting an acceleration of the vehicle and outputting an acceleration signal representative thereof, comprising: at least one front acceleration sensor, provided in a front part of the vehicle, for detecting the acceleration of the vehicle and giving a sensor output representative thereof; and a control unit, connected to said room acceleration sensor and said front acceleration sensor, for inputting the acceleration signal of said room acceleration sensor and the sensor output of said front acceleration sensor, and for driving the occupant protection device when an integrated value of the acceleration signal of said room acceleration sensor exceeds a predetermined threshold value, said control unit detecting a variational quantity of the sensor output of said front acceleration sensor based on sensor outputs of said front acceleration sensor at two different time points when the sensor output of said front acceleration sensor is a sensor output caused by a collision of the vehicle, and increasing the integrated value of said room acceleration sensor based on the variational quantity of said front acceleration sensor.
According to a composition like this, when the sensor output of the front acceleration sensor is a sensor output caused by a collision, the variational quantity of the sensor output of the front acceleration sensor is detected based on sensor outputs of the front acceleration sensor at two different time points. Then, the integrated value of the acceleration signal of the room acceleration sensor is increased based on the variational quantity of the front acceleration sensor. Since the front acceleration sensor is provided in the front part of the vehicle, even when a collision acceleration transmitted to the room acceleration sensor is weakened, the front acceleration sensor detects the collision acceleration early and gives the sensor output to the control unit. By this, since the integrated value of the room acceleration sensor is increased based on the variational quantity of the front acceleration sensor, the control unit can drive the occupant protection device without causing delay in collision decision.
The above and other objects are also attained by a control apparatus of an occupant protection device having a room acceleration sensor, provided in a room of a vehicle, for detecting an acceleration of the vehicle and outputting an acceleration signal representative thereof, comprising: at least one front acceleration sensor, provided in a front part of the vehicle, for detecting the acceleration of the vehicle and giving a sensor output representative thereof; and a control unit, connected to said room acceleration sensor and said front acceleration sensor, for inputting the acceleration signal of said room acceleration sensor and the sensor output of said front acceleration sensor, and for driving the occupant protection device when an integrated value of the acceleration signal of said room acceleration sensor exceeds a threshold value, said control unit detecting a variational quantity of the sensor output of said front acceleration sensor based on sensor outputs of said front acceleration sensor at two different time points when the sensor output of said front acceleration sensor is a sensor output caused by a collision of the vehicle, and decreasing the threshold value toward the integrated value of the room acceleration sensor based on the variational quantity of said front acceleration sensor.
According to a composition like this, the threshold value toward the integrated value of the acceleration signal of the room acceleration sensor is decreased based on the variational quantity of the sensor output of the front acceleration sensor. Because of this, the integrated value of the room acceleration sensor exceeds the threshold value without causing delay, and the occupant protection device is exactly driven.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.